O04 Clinical significance and prevelance of postinterventional subarachnoidal hyperdensities on flat-detector CT after mechanical thrombectomy in dominant, co- and non-dominant M2 occlusions: a mutlicentric study

<h3>Introduction</h3> Subarachnoidal hyperdensities (SH) on flat detector CT (FDCT) after mechanical thrombectomy (MT) are associated with neurological incline and less favorable clinical outcome; SH are more common in distal occlusions and after multiple device passes. With technical advancements, neurointerventionalists are aiming to treat further distal occlusions, with several randomized trials underway <h3>Aim of Study</h3> We aimed to further identify the prevalence and clinical significance of SH on FDCT following MT, especially in patients with dominant, co- and non-dominant caliber M2 occlusions <h3>Methods</h3> 640 patients from two comprehensive stroke were analyzed for the presence of SH on FDCT and then classified according to a visual grading scale. 351 patients were included. The primary outcome was mRS at 90 days and was analyzed with the Wilcoxon-Mann-Whitney rank-sum test. To identify predictors regression analysis, Kruskal-wallis analysis and X² test were performed <h3>Results</h3> Prevalence of SH on FDCT was 144/351 (40.9%) with patients experiencing a significant more unfavorable outcome (p=0.014). Distal occlusions and a higher number of device passes were significantly associated with SH (P&lt;0.001) and (P=0.006), respectively. SH was significantly more frequent (p=0.014) in co- and non-dominant M2 occlusions 41/63 (65.07%) compared to dominant M2 occlusions 35/79 (44.3%), with a significant effect p &lt;0.001 OR= 4.18 (95%CI 2.28-7.69). Higher number of device passes &gt;3 and &lt; 6 had a significant effect on the occurrence of SH P&lt; 0.001 OR= 3.42 (95%CI 1.76-6.67). <h3>Conclusion</h3> SH is associated with worse functional outcome, with co- and non-dominant M2 occlusions and higher numbers of device passes &gt;3. <h3>Disclosure of Interest</h3> no.